The aforementioned Zimmerman patent describes a system wherein the dry concrete constituents or ingredients are stored in separate storage compartments in a mobile unit and are selectively fed in predetermined portions to a mixing trough. The ingredients are mixed with water in the trough to form concrete of a desired characteristic. The trough includes an auger extending longitudinally therethrough which is rotated by a motor to simultaneously mix the various constituents while delivering the total mixture through a trough discharge opening at the distal end of the trough. The trough is secured to the component-storing vehicle so as to be movable about both a horizontally-extending axis and a vertically-extending axis, thereby to deliver the concrete from a variety of different orientations relative to the vehicle. Since the trough is permanently secured to the vehicle, there is a limitation as to the permissible length of the trough in order for the trough to be safely and conveniently stored when not in use. This limitation on trough length has brought about the need for the attachment of delivery chutes to the end of the trough so that the concrete can be delivered to a location beyond the reach of the trough. These extension chutes are typically stored in separate locations and attached to the trough manually. This procedure, whereby the chutes are manually secured to the trough, attached to one another, adjusted in position, removed after delivery, and stored, is exceedingly time consuming. Moreover, once the chutes are loaded, changing position of the trough and chutes cannot be accomplished without removing the concrete remaining in the chutes.